How do socioeconomic attainment gaps in early mathematical ability arise?

Socioeconomic attainment gaps in mathematical ability are evident before children begin school, and widen over time. Little is known about why early attainment gaps emerge. Two cross-sectional correlational studies were conducted in 2018-2019 with socioeconomically diverse preschoolers, to explore four factors that might explain why attainment gaps arise: working memory, inhibitory control, verbal ability, and frequency of home mathematical activities (N = 304, 54% female; 84% White, 10% Asian, 1% black African, 1% Kurdish, 4% mixed ethnicity). Inhibitory control and verbal ability emerged as indirect factors in the relation between socioeconomic status and mathematical ability, but neither working memory nor home activities did. We discuss the implications this has for future research to understand, and work towards narrowing attainment gaps.

Parent Training for ADHD: No Generalization of Effects From Clinical to Neuropsychological Outcomes in a Randomized Controlled Trial

OBJECTIVE

We examined whether neuropsychological function in ADHD can be improved by the New Forest Parenting Programme (NFPP), that combines standard parenting strategies with self-regulatory skills training, or predict ADHD and quality of life (QoL) treatment effects.

METHOD

Participants were 93 medication-naive preschool children with ADHD (3-7 years) randomized to either NFPP (n = 49) or treatment as usual (TAU; n = 44) in a recent randomized trial. Laboratory measures of executive function, reaction time variability, and delay of gratification were collected along with parent ratings of ADHD and QoL at baseline and post treatment. Ratings were collected again at 3-month follow-up.

RESULTS

NFPP did not improve neuropsychological function (compared to TAU), and baseline neuropsychological function did not predict treatment-related ADHD or QoL effects.

CONCLUSION

Although NFPP includes a neuropsychological training element and has been shown to improve several clinical outcomes, it did not improve the neuropsychological functions it targets.

The Effect of Social Presence on Mentalizing Behavior

Our behavior is frequently influenced by those around us. However, the majority of social cognition research is conducted using socially isolated paradigms, without the presence of real people (i.e., without a "social presence"). The current study aimed to test the influence of social presence upon a measure of mentalizing behavior in adults. Study 1 used a first-order theory of mind task; and study 2 used a second-order theory of mind task. Both studies included two conditions: live, where the task protagonists were physically present acting out the task, or recorded, where the same task protagonists demonstrated the task in a video recording. In both experiments, participants were affected by the social presence and demonstrated significantly different patterns of behavior in response to the presence of real people. This study, therefore, highlights the critical importance of understanding the effect of a social presence in mentalizing research, and suggests that the inclusion of a social presence needs to be given strong consideration across social cognition paradigms.

Why are some inhibitory tasks easy for preschool children when most are difficult? Testing two hypotheses

Understanding the processes that create inhibitory demands is central to understanding the role of inhibitory control in all aspects of development. The processes that create inhibitory demands on most developmental tasks seem clear and well understood. However, there is one inhibitory task that appears substantially easier than the others: the Reverse Categorization task, in which children are asked to "reverse sort" items (e.g., put large items in a small box and put small items in a large box). This finding is both surprising and problematic because it cannot be explained by any existing account of inhibitory development. Four experiments with 3- and 4-year-olds sought to explain why the Reverse Categorization task is easy. Two experiments (N = 64) investigated the hypothesis that children conceptualize the task in a way that reduces its inhibitory demands; and two experiments (N = 56) tested the hypothesis that the task is easier because children sort items slowly. The data indicate that children spontaneously respond more slowly on the Reverse Categorization task than on other inhibitory tasks and that this slowing reduces the task's cognitive demands. The way in which slowed responding works, and its relation to other inhibition-reducing interventions, is discussed.

Can We Boost Preschoolers' Inhibitory Performance Just by Changing the Way They Respond?

Changing the way children make their response appears to sometimes, but not always, boost their inhibitory control-though interpreting existing findings is hampered by inconsistent methods and results. This study investigated the effects of delaying, and changing, the means of responding. Ninety-six preschoolers (M_age 46 months) completed tasks assessing inhibitory control, counterfactual reasoning, strategic reasoning, and false belief understanding. Children responded either immediately or after a delay, and either by pointing with their finger, or with a hand-held arrow. Delaying boosted performance on all tasks except false belief understanding; arrow-pointing only improved strategic reasoning. It is suggested that delay helps children work out the correct response; it is unlikely to help on tasks where this requirement is absent.

The Role of Executive Functions in Socioeconomic Attainment Gaps: Results From a Randomized Controlled Trial

The socioeconomic attainment gap in mathematics starts early and increases over time. This study aimed to examine why this gap exists. Four-year-olds from diverse backgrounds were randomly allocated to a brief intervention designed to improve executive functions (N = 87) or to an active control group (N = 88). The study was preregistered and followed CONSORT guidelines. Executive functions and mathematical skills were measured at baseline, 1 week, 3 months, 6 months, and 1 year posttraining. Executive functions mediated the relation between socioeconomic status and mathematical skills. Children improved over training, but this did not transfer to untrained executive functions or mathematics. Executive functions may explain socioeconomic attainment gaps, but cognitive training directly targeting executive functions is not an effective way to narrow this gap.

Elevated Depressive Symptoms Among Hired Crop Workers in the United States: Variation by Sociodemographic and Employment Characteristics

We present prevalence rates, along with demographic and economic characteristics associated with elevated depressive symptoms (EDS), in a nationally representative sample of hired crop workers in the United States. We analyzed in-person interviews with 3,691 crop workers collected in 2009-2010 as part of a mental health and psychosocial supplement to the National Agricultural Workers Survey. The prevalence of EDS was 8.3% in men and 17.1% in women. For men, multivariate analysis showed that EDS was associated with years of education, family composition, having a great deal of difficulty being separated from family, having fair or poor general health, ability to read English, fear of being fired from their current farm job, and method of payment (piece, salary, or a combination). Interactions were found between region of the country and family composition. Multivariate analyses for women showed that fear of being fired, fair or poor general health, having children ≤15 years of age, being unaccompanied by their nuclear family, expectation for length of time continuing to do farm work in the United States, and authorization status were associated with EDS. Interactions were found with Hispanic ethnicity and region of the country, as well as presence of the nuclear family and region. The present study identifies important risk factors in this first population-based assessment of EDS in a nationally representative sample of U.S. crop workers. The importance of social support from family, job insecurity, and high prevalence of EDS in female crop workers support the need for screening and outreach in this primarily rural group of men and women crop workers.

Young children can overcome their weak inhibitory control, if they conceptualize a task in the right way

This article investigates the process of task conceptualization, through which participants turn the instructions on a task into a mental representation of that task. We provide the first empirical evidence that this process of conceptualization can directly influence the inhibitory demands of a task. Data from Experiments 1 and 2 (both n = 24) suggested that robust difficulties on inhibitory tasks can be overcome if preschoolers conceptualize the tasks in a way that avoids the need for inhibitory control. Experiment 3 (n = 60) demonstrated that even when all other aspects of a task are identical, simply changing how the rules are introduced can influence whether such a conceptualization is adopted - thereby influencing children's performance on the task. An appreciation of the process of conceptualization is essential for our understanding of how inhibitory control and knowledge interact in early development.

Neural Correlates of Response Inhibition in Early Childhood: Evidence From a Go/No-Go Task

We examined the neural correlates underlying response inhibition in early childhood. Five-year-old children completed a Go/No-go task with or without time pressure (Fast vs. Slow condition) while scalp EEG was recorded. On No-go trials where inhibition was required, the left frontal N2 and posterior P3 were enhanced relative to Go trials. Time pressure was detrimental to behavioral performance and modulated the early-occurring P1 component. The topography of ERPs related to response inhibition differed from patterns typically seen in adults, and may indicate a compensatory mechanism to make up for immature inhibition networks in children.

The feasibility of pediatric TORS for lingual thyroglossal duct cyst

A six-year-old boy who presented with symptoms of obstructive sleep apnea was found to have a midline tongue mass suspicious for lingual thyroglossal duct cyst (TGDC). Surgery was scheduled after workup confirmed the presence of functional, orthotopic thyroid tissue. The surgical robot was used to excise the mass endoscopically without removing any hyoid. He was extubated at the conclusion of the case. The child tolerated a soft diet and was discharged after an uneventful overnight stay in the ICU. Pathology confirmed TGDC. There have been no reported issues in eleven months of follow-up. Our report adds to the scarce literature on performing such a surgery in a child and demonstrates that with the correct circumstances, prompt extubation, discharge, and prolonged remission are possible.

Different Executive Functions Support Different Kinds of Cognitive Flexibility: Evidence From 2-, 3-, and 4-Year-Olds

Improvements in cognitive flexibility during the preschool years have been linked to developments in both working memory and inhibitory control, though the precise contribution of each remains unclear. In the current study, one hundred and twenty 2-, 3-, and 4-year-olds completed two rule-switching tasks. In one version, children switched rules in the presence of conflicting information, and in the other version, children switched rules in the presence of distracting information. Switching in the presence of conflict improved rapidly between the ages of 3 and 3.5 years, and was associated with better working memory. Conversely, switching in the presence of distraction developed significantly between the ages of 2 and 3 years, and was associated with better inhibitory control.

A Short Executive Function Training Program Improves Preschoolers' Working Memory

Cognitive training has been shown to improve executive functions (EFs) in middle childhood and adulthood. However, fewer studies have targeted the preschool years-a time when EFs undergo rapid development. The present study tested the effects of a short four session EF training program in 54 four-year-olds. The training group significantly improved their working memory from pre-training relative to an active control group. Notably, this effect extended to a task sharing few surface features with the trained tasks, and continued to be apparent 3 months later. In addition, the benefits of training extended to a measure of mathematical reasoning 3 months later, indicating that training EFs during the preschool years has the potential to convey benefits that are both long-lasting and wide-ranging.

Attentional processes in low-socioeconomic status bilingual children: are they modulated by the amount of bilingual experience?

Recent research indicates that bilingual children are more proficient in resolving cognitive conflict than monolinguals. However, the replicability of such findings has been questioned, with poor control of participants' socioeconomic status (SES) as a possible confounding factor. Two experiments are reported here, in which the main attentional functions and pragmatic ability of 54 bilingual and 56 monolingual low-SES children were assessed (Experiment 1: 6- to 12-year-olds; Experiment 2: 6- to 8-year-olds). A language-switching task was also employed, to measure bilingual proficiency. Overall, the monolingual and bilingual groups did not differ significantly in any of the tasks employed, although the ability to resolve conflict was related to children's level of bilingual experience.

Evaluating Job Demands and Control Measures for Use in Farm Worker Health Surveillance

Workplace stress likely plays a role in health disparities; however, applying standard measures to studies of immigrants requires thoughtful consideration. The goal of this study was to determine the appropriateness of two measures of occupational stressors ('decision latitude' and 'job demands') for use with mostly immigrant Latino farm workers. Cross-sectional data from a pilot module containing a four-item measure of decision latitude and a two-item measure of job demands were obtained from a subsample (N = 409) of farm workers participating in the National Agricultural Workers Survey. Responses to items for both constructs were clustered toward the low end of the structured response-set. Percentages of responses of 'very often' and 'always' for each of the items were examined by educational attainment, birth country, dominant language spoken, task, and crop. Cronbach's α, when stratified by subgroups of workers, for the decision latitude items were (0.65-0.90), but were less robust for the job demands items (0.25-0.72). The four-item decision latitude scale can be applied to occupational stress research with immigrant farm workers, and potentially other immigrant Latino worker groups. The short job demands scale requires further investigation and evaluation before suggesting widespread use.

Primed to be inflexible: the influence of set size on cognitive flexibility during childhood

One of the hallmarks of human cognition is cognitive flexibility, the ability to adapt thoughts and behaviors according to changing task demands. Previous research has suggested that the number of different exemplars that must be processed within a task (the set size) can influence an individual's ability to switch flexibly between different tasks. This paper provides evidence that when tasks have a small set size, children's cognitive flexibility is impaired compared to when tasks have a large set size. This paper also offers insights into the mechanism by which this effect comes about. Understanding how set size interacts with task-switching informs the debate regarding the relative contributions of bottom-up priming and top-down control processes in the development of cognitive flexibility. We tested two accounts for the relationship between set size and cognitive flexibility: the (bottom-up) Stimulus-Task Priming account and the (top-down) Rule Representation account. Our findings offered support for the Stimulus-Task Priming account, but not for the Rule Representation account. They suggest that children are susceptible to bottom-up priming caused by stimulus repetition, and that this priming can impair their ability to switch between tasks. These findings make important theoretical and practical contributions to the executive function literature: theoretically, they show that the basic features of a task exert a significant influence on children's ability to flexibly shift between tasks through bottom-up priming effects. Practically, they suggest that children's cognitive flexibility may have been underestimated relative to adults', as paradigms used with children typically have a smaller set size than those used with adults. These findings also have applications in education, where they have the potential to inform teaching in key areas where cognitive flexibility is required, such as mathematics and literacy.

What's so special about verbal imitation? Investigating the effect of modality on automaticity in children

Young children experience difficulty across a wide variety of situations that require them to suppress automatic responses. Verbal imitation, in contrast, is easy for children to suppress. This is all the more surprising because data from adult studies appear to be at odds with this observation. In two experiments, we investigated whether this surprising developmental finding with verbal imitation reflects a more general phenomenon-relating either to verbal responses or to auditory stimuli-or whether verbal imitation itself represents a unique case. In Experiment 1 (N=24), it was found that verbal responses were not inherently easier for 3-year-olds to inhibit than manual responses. Experiment 2 (N=24) showed that auditory stimuli did not evoke less automatic activation than visual stimuli. Taken together, these data suggest that verbal imitation is unique, or at least unusual, in being particularly easy for children to resist. It is suggested that the automaticity of verbal imitation may develop slowly and that the relation between word complexity and automaticity is likely to be a fruitful topic of further investigation.

Why do alternative ways of responding improve children's performance on tests of strategic reasoning?

Changing the way in which children respond significantly improves performance across a variety of cognitive domains. However, the basis for this response-mode effect is unknown. To address this issue, the current study tested 78 preschool children on a measure of executive functioning (the windows task: Hala & Russell, ). The task requires children to point to an empty box to receive a box with a treat in it. There were four versions of the task, differing only in the way in which children made their responses. Children in the baseline condition, who pointed with their finger, performed poorly. However, children in three alternative response-mode conditions won the treat significantly more often. Strikingly, even children who pretended to be pointing with an arrow - but were in reality pointing with their finger - performed significantly better than baseline. We suggest that non-standard response modes encourage children to reflect on their actions and that this reduces the number of unreflective errors they make. The findings demonstrate that response-mode effects do not depend on the presence of a physical means of responding (such as an arrow), but can be achieved via a purely cognitive means (such as engaging in pretence).

The effect of cleft palate repair technique on hearing outcomes in children

OBJECTIVE

Otitis media with effusion causing conductive hearing loss is a problem for many children with cleft palate. This study examines the association between palate repair technique and hearing outcomes in children at 3 and 6 years post-repair.

PATIENTS AND METHODS

Retrospective chart review of patients with all types of cleft palate that were repaired between 2001 and 2006 at a tertiary children's hospital. Exclusion criteria included sensorineural hearing loss, ossicular chain abnormalities, and ear canal abnormalities. The primary outcome was pure tone average (PTA) from 0.5 kHz to 2 kHz.

RESULTS

69 patients (138 ears) were analyzed. 30.4% of left ears and 31.9% of right ears had an abnormal (>20 dB) PTA at 3 years; at 6 years this significantly improved to 13.0% (p=0.008) and 15.9% (p=0.011). Double-reverse z-plasty was associated with the lowest median PTA of 10.0 dB (p=0.046) at 6 years. There was no difference in median PTA between children with and without comorbid diagnoses (such as Pierre Robin Sequence, arthrogryposis) at either 3 years or 6 years (p=0.075, p=0.331). Multivariate model showed that extent of cleft influenced technique choice (p=0.027), but only technique choice was associated with significant differences in PTA and only at 6 years post-repair.

CONCLUSION

The majority of children developed normal hearing by 6 years with palatoplasty and routine tube insertion. Double reverse z-plasty was associated with the best outcome, but is not ideal for hard palate clefts. Randomized controlled trials are needed to elucidate the relationship between technique, middle ear ventilation and time to recovery, irrespective of type of cleft.

How do alternative ways of responding influence 3- and 4-year-olds' performance on tests of executive function and theory of mind?

A total of 69 preschool children were tested on measures of false belief understanding (the Unexpected Transfer task), inhibitory control (the Grass/Snow task), and strategic reasoning (the Windows task). For each task, children indicated their response either by pointing with their index finger or by using a nonstandard response mode (pointing with a rotating arrow). The means of responding had no effect on children's performance on the Grass/Snow task or on the Unexpected Transfer task, although children performed better on the Unexpected Transfer task when the key object in the story was removed. In contrast, performance on the Windows task was significantly better when children pointed with the rotating arrow. A follow-up experiment with 79 preschoolers found that this improved performance on the Windows task was sustained even after the nonstandard response mode was removed and children again pointed with their finger. These findings together suggest that nonstandard response modes do not help children to inhibit prepotent pointing responses but may help them to formulate response strategies on reasoning tasks by discouraging unreflective impulsive responding.

Mental health research with Latino farmworkers: a systematic evaluation of the short CES-D

Mental health research among Latino farmworkers is hampered by the absence of measurement evaluation that ensures farmworkers understand and can consistently and appropriately respond to questions about mental health. Cross-sectional data were obtained from 409 farmworkers via interviewer-administered survey questionnaires. Mental health was operationalized with the short-form Center for Epidemiologic Studies, Depression (CES-D) scale. The structured interviewer-administered survey questionnaires included measures to capture personal and work-related factors that could affect farmworkers' ability to understand and respond to mental health questions probed by the CES-D. Good variability in item response was observed across the 10 short-form CES-D items. There was no evidence of differential response across sub-groups of farmworkers for six of the 10 items. Responses to four of the 10 items differed by educational attainment, country of origin, and language preference. Overall, the internal consistency of the 10 items exceeded standard conventions, and observed differences in depressive symptoms were as expected. Researchers in farmworker mental health must remain attentive to the strength and validity of available measures for migrants, different ethnic groups and different socioeconomic backgrounds. Nevertheless, the overall pattern suggests that the CES-D is a viable tool for advancing farmworker mental health research.

Why are there limits on theory of mind use? Evidence from adults’ ability to follow instructions from an ignorant speaker

Keysar et al. (Keysar, Barr, Balin, & Brauner, 2000; Keysar, Lin, & Barr, 2003) report that adults frequently failed to use their conceptual competence for theory of mind (ToM) in an online communication game where they needed to take account of a speaker's perspective. The current research reports 3 experiments investigating the cognitive processes contributing to adults’ errors. In Experiments 1 and 2 the frequency of adults’ failure to use ToM was unaffected by perspective switching. In Experiment 3 adults made more errors when interpreting instructions according to the speaker's perspective than according to an arbitrary rule. We suggest that adults are efficient at switching perspectives, but that actually using what another person knows to interpret what they say is relatively inefficient, giving rise to egocentric errors during communication.

Choosing between two objects reduces 3-year-olds’ errors on a reverse-contingency test of executive function

In the present experiment, we used a reversed-contingency paradigm (the windows task: [Russell, J., Mauthner, N., Sharpe, S., & Tidswell, T. (1991). The windows task as a measure of strategic deception in preschoolers and autistic subjects. British Journal of Developmental Psychology, 9, 331-349]) to explore the effect of alterations in the task array on 3-year-old children's strategic reasoning. Children were offered a choice between either a desirable object and an undesirable object, or between a desirable object and an empty location. There was significantly better performance on the two-object version of the task. This difference was evident even on subsequent trials when the second object was removed and the empty location reintroduced. This suggests that presenting children with a choice between two objects helps them to formulate a strategy, rather than to execute a previously determined response.

Children's thinking about counterfactuals and future hypotheticals as possibilities

Two experiments explored whether children's correct answers to counterfactual and future hypothetical questions were based on an understanding of possibilities. Children played a game in which a toy mouse could run down either 1 of 2 slides. Children found it difficult to mark physically both possible outcomes, compared to reporting a single hypothetical future event, "What if next time he goes the other way ..." (Experiment 1: 3-4-year-olds and 4-5-year-olds), or a single counterfactual event, "What if he had gone the other way ...?" (Experiment 2: 3-4-year-olds and 5-6-year-olds). An open counterfactual question, "Could he have gone anywhere else?," which required thinking about the counterfactual as an alternative possibility, was also relatively difficult.

Agricultural injury in California migrant Hispanic farm workers

BACKGROUND

Agriculture is among the most hazardous industries in the United States.

METHODS

A longitudinal study of injury among migrant Hispanic farm workers residing in six Northern California Migrant Family Housing Centers (MHCs) during the 1997 harvest season was conducted. Participants completed an initial interviewer-administered work-and-health questionnaire at the beginning of the harvest season addressing the preceding year; there were three periodic follow-up surveys.

RESULTS

There were 1,201 adult farm workers (participation 85.2%) who completed the initial questionnaire. Of these, 837 (69.7%) completed the final follow-up survey. There were 86 agricultural injuries (incidence 9.3/100 full-time equivalent employees (FTEs), 95% CI 7.5-11.5/100 FTE). Increased risk for agricultural injury occurred among women paid piece-rate (RR 4.9, 95% CI 1.8-12.8). Sprains and strains were most common (31%), followed by lacerations (12%).

CONCLUSIONS

Agricultural injury experience in this cohort is comparable to that of agricultural workers in other U.S. settings. Increased risk among women paid piece-rate suggests further study and potential policy changes regarding payment regimens. Heterogeneity of injury in this population presents a major prevention challenge. In view of high frequency of strain and sprain injuries, ergonomic interventions deserve further study.

Injury risks in children of California migrant Hispanic farm worker families

BACKGROUND

Few data are available addressing occupational and other injury risks among children of migrant Hispanic farm workers.

METHODS

We conducted the U.C. Davis Farm Worker Injury Study (UCD-FWIS), a longitudinal follow-up study of injury among migrant Hispanic farm worker families living in six Northern California Migrant Housing Centers (MHCs). Nine hundred forty-one children (age < 18 years) were interviewed through parental proxy.

RESULTS

Fifty-one injuries resulting in medical care or at least one-half day of lost or restricted work or school time occurred among 49 children (3.8 injuries/100 person-years). Open wounds (31.4%) and fractures (29.4%) were most common. Falls comprised over one-third of the cases, followed by being struck and bicycle injuries. Over three-quarters of subjects never use a helmet when riding a bicycle. Seventy-eight (8.3%) children reported employment in the preceding year, typically involving manual agricultural tasks. Two injury cases were occupational and involved agricultural work.

CONCLUSIONS

Occupational injury was uncommon in this group of children in migrant Hispanic farm worker families. Injury prevention in this population should include a focus on the home and surrounding environment as well as the work place.

Calcium-mediated inactivation of the MAP kinase pathway in sea urchin eggs at fertilization

We have evaluated the regulation of a 43-kDa MAP kinase in sea urchin eggs. Both MAP kinase and MEK (MAP kinase kinase) are phosphorylated and active in unfertilized eggs while both are dephosphorylated and inactivated after fertilization, although with distinct kinetics. Reactivation of MEK or the 43-kDa MAP kinase prior to or during the first cell division was not detected. Confocal immunolocalization microscopy revealed that phosphorylated (active) MAP kinase is present primarily in the nucleus of the unfertilized egg, with some of the phosphorylated form in the cytoplasm as well. Incubation of unfertilized eggs in the MEK inhibitor U0126 (0.5 microM) resulted in the inactivation of MEK and MAP kinase within 30 min. Incubation in low concentrations of U0126 (sufficient to inactivate MEK and MAP kinase) after fertilization had no effect on progression through the embryonic cell cycle. Microinjection of active mammalian MAP kinase phosphatase (MKP-3) resulted in inactivation of MAP kinase in unfertilized eggs, as did addition of MKP-3 to lysates of unfertilized eggs. Incubation of unfertilized eggs in the Ca(2+) ionophore A23187 led to inactivation of MEK and MAP kinase with the same kinetics as observed with sperm-induced egg activation. This suggests that calcium may be deactivating MEK and/or activating a MAP kinase-directed phosphatase. A cell-free system was used to evaluate the activation of phosphatase separately from MEK inactivation. Unfertilized egg lysates were treated with U0126 to inactivate MEK and then Ca(2+) was added. This resulted in increased MAP kinase phosphatase activity. Therefore, MAP kinase inactivation at fertilization in sea urchin eggs likely is the result of a combination of MEK inactivation and phosphatase activation that are directly or indirectly responsive to Ca(2+).

Ca2+ signalling during fertilization of echinoderm eggs

The Ca2+ rise at fertilization of echinoderm eggs is initiated by a process requiring the sequential activation of a Src family kinase, phospholipase C gamma, and the inositol trisphosphate receptor/channel in the endoplasmic reticulum. The consequences of the Ca2+ rise include exocytosis of cortical granules, which establishes a block to polyspermy, and inactivation of MAP kinase, which functions in linking the Ca2+ rise to the reinitiation of the cell cycle.

Agricultural injury

BACKGROUND

Agriculture is one of the most hazardous industries in the US.

METHODS

We reviewed MEDLINE and NIOSHTIC to identify English-language studies addressing occupational injury among agricultural populations, focusing on North America. Additional references were identified from the reference lists of identified studies and from contacts with experts in the field.

RESULTS

U.S. data indicate up to approximately 780 deaths and 140,000 cases of nonfatal disabling injuries in 1998. Risk of agricultural injuries is approximately 5-10/100 persons per year, but is higher in certain risk groups, such as males and cattle workers. Falls, machinery, and animals are among the most common causes. Unique features of the agricultural workplace and exposed population combine to increase risk and hinder accurate measurement. These features include a wide range of activities, hazards, and dispersed work places in agriculture; a seasonal hired work force that often has brief tenure, poor English skills, and a distrust of officialdom; and a history of exemption regarding occupational health and safety regulations.

CONCLUSIONS

Research in agricultural injury should include epidemiologic study of risk factors and evaluation of interventions. Although only limited data are available documenting efficacy of specific preventive approaches, prevention should focus on engineering controls, regulatory approaches, and education.

Evidence that Src-type tyrosine kinase activity is necessary for initiation of calcium release at fertilization in sea urchin eggs

The initiation of Ca(2+) release from internal stores in the egg is a hallmark of egg activation. In sea urchins, PLCgamma activity is necessary for the production of IP(3), which leads to the initial rise in Ca(2+). To examine the possible function of a tyrosine kinase in activating PLCgamma at fertilization, sea urchin eggs were treated with the specific Src kinase inhibitor PP1 or microinjected with recombinant Src-family SH2-domain proteins, which act as dominant interfering inhibitors of Src-family kinase function. Both modes of inhibiting Src-family kinases resulted in a specific and dose-dependent delay in the onset of Ca(2+) release from the endoplasmic reticulum at fertilization. The rise in cytoplasmic pH at fertilization also was inhibited by microinjection of Src-family SH2-domain proteins. Further, an antibody directed against Src-type kinases recognized a protein of ca. M(r) 57K that was enriched in the membrane fraction of eggs. The kinase activity of this protein was stimulated rapidly and transiently at fertilization, as measured by autophosphorylation and by phosphorylation of an exogenous substrate. Together, these data indicate that a Src-type tyrosine kinase is necessary for the initiation of Ca(2+) release from the egg ER at fertilization and identify a Src-type p57 protein as a candidate in the signaling pathway leading to this Ca(2+) release.

The relationship between calcium, MAP kinase, and DNA synthesis in the sea urchin egg at fertilization

Fertilization releases the brake on the cell cycle and the egg completes meiosis and enters into S phase of the mitotic cell cycle. The MAP kinase pathway has been implicated in this process, but the precise role of MAP kinase in meiosis and the first mitotic cell cycle remains unknown and may differ according to species. Unlike the eggs of most animals, sea urchin eggs have completed meiosis prior to fertilization and are arrested at the pronuclear stage. Using both phosphorylation-state-specific antibodies and a MAP kinase activity assay, we observe that MAP kinase is phosphorylated and active in unfertilized sea urchin eggs and then dephosphorylated and inactivated by 15 min postinsemination. Further, Ca(2+) was both sufficient and necessary for this MAP kinase inactivation. Treatment of eggs with the Ca(2+) ionophore A23187 caused MAP kinase inactivation and triggered DNA synthesis. When the rise in intracellular Ca(2+) was inhibited by injection of a chelator, BAPTA or EGTA, the activity of MAP kinase remained high. Finally, inhibition of the MAP kinase signaling pathway by the specific MEK inhibitor PD98059 triggered DNA synthesis in unfertilized eggs. Thus, whenever MAP kinase activity is retained, DNA synthesis is inhibited while inactivation of MAP kinase correlates with initiation of DNA synthesis.

Requirement of a Src family kinase for initiating calcium release at fertilization in starfish eggs

Signal transduction leading to calcium release in echinoderm eggs at fertilization requires phospholipase Cgamma-mediated production of inositol trisphosphate (IP(3)), indicating that a tyrosine kinase is a likely upstream regulator. Because previous work has shown a fertilization-dependent association between the Src homology 2 (SH2) domains of phospholipase Cgamma and a Src family kinase, we examined whether a Src family kinase was required for Ca(2+) release at fertilization. To inhibit the function of kinases in this family, we injected starfish eggs with the SH2 domains of Src and Fyn kinases. This inhibited Ca(2+) release in response to fertilization but not in response to injection of IP(3). We further established the specificity of the inhibition by showing that the SH2 domains of several other tyrosine kinases (Abl, Syk, and ZAP-70), and the SH3 domain of Src, were not inhibitory. Also, a point-mutated Src SH2 domain, which has reduced affinity for phosphotyrosine, was a correspondingly less effective inhibitor of fertilization-induced Ca(2+) release. These results indicate that a Src family kinase, by way of its SH2 domain, links sperm-egg interaction to IP(3)-mediated Ca(2+) release at fertilization in starfish eggs.

Inventing the future of physicians and information technology: methods and results of the 1997 Lafayette Parish Medical Society Information Systems and Information Technology Project

This paper challenges physicians to consider how to best invent a future in which they can personally leverage emerging information and communication technologies to maximize their effectiveness and efficiency as care givers. One Louisiana State Medical Society component medical society has already posed this challenge to its members. The paper describes the 1997 Lafayette Parish Medical Society Physicians' Information Systems and Information Project, conducted on behalf of the society by faculty of the Healthcare Administration MBA Program at the University of Southwestern Louisiana. Specific recommendations for application of health care information technologies by physicians and by health care institutions, based on findings and conclusions of the project, are highlighted.

Evidence that a starfish egg Src family tyrosine kinase associates with PLC-gamma1 SH2 domains at fertilization

The initiation of calcium release at fertilization in the eggs of most animals relies on the production of IP3, implicating the activation of phospholipase C. Recent work has demonstrated that injection of PLC-gamma SH2 domain fusion proteins into starfish eggs specifically inhibits the initiation of calcium release in response to sperm, indicating that PLC-gamma is necessary for Ca2+ release at fertilization [Carroll et al. (1997) J. Cell Biol. 138, 1303-1311]. Here we investigate how PLC-gamma may be activated, by using the PLC-gamma SH2 domain fusion protein as an affinity matrix to identify interacting proteins. A tyrosine kinase activity and an egg protein of ca. Mr 58 K that is recognized by an antibody directed against Src family tyrosine kinases associate with PLC-gamma SH2 domains in a fertilization-dependent manner. These associations are detected by 15 s postfertilization, consistent with a function in releasing Ca2+. Calcium ionophore treatment of eggs did not cause association of the kinase activity or of the Src family protein with the PLC-gamma SH2 domains. These data identify an egg Src family tyrosine kinase as a potential upstream regulator of PLC-gamma in the activation of starfish eggs.

Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs

At fertilization, sea urchin eggs undergo a series of activation events, including a Ca2+ action potential, Ca2+ release from the endoplasmic reticulum, an increase in intracellular pH, sperm pronuclear formation, MAP kinase dephosphorylation, and DNA synthesis. To examine which of these events might be initiated by activation of phospholipase Cgamma (PLCgamma), which produces the second messengers inositol trisphosphate (IP3) and diacylglycerol, we used recombinant SH2 domains of PLCgamma as specific inhibitors. Sea urchin eggs were co-injected with a GST fusion protein composed of the two tandem SH2 domains of bovine PLCgamma and (1) Ca2+ green dextran to monitor intracellular free Ca2+, (2) BCECF dextran to monitor intracellular pH, (3) Oregon Green dUTP to monitor DNA synthesis, or (4) fluorescein 70-kDa dextran to monitor nuclear envelope formation. Microinjection of the tandem SH2 domains of PLCgamma produced a concentration-dependent inhibition of Ca2+ release and also inhibited cortical granule exocytosis, cytoplasmic alkalinization, MAP kinase dephosphorylation, DNA synthesis, and cleavage after fertilization. However, the Ca2+ action potential, sperm entry, and sperm pronuclear formation were not prevented by injection of the PLCgammaSH2 domain protein. Microinjection of a control protein, the tandem SH2 domains of the phosphatase SHP2, had no effect on Ca2+ release, cortical granule exocytosis, DNA synthesis, or cleavage. Specificity of the inhibitory action of the PLCgammaSH2 domains was further indicated by the finding that microinjection of PLCgammaSH2 domains that had been point mutated at a critical arginine did not inhibit Ca release at fertilization. Additionally, Ca2+ release in response to microinjection of IP3, cholera toxin, cADP ribose, or cGMP was not inhibited by the PLCgammaSH2 fusion protein. These results indicate that PLCgamma plays a key role in several fertilization events in sea urchin eggs, including Ca2+ release and DNA synthesis, but that the action potential, sperm entry, and male pronuclear formation can occur in the absence of PLCgamma activation or Ca2+ increase.

Calcium release at fertilization in starfish eggs is mediated by phospholipase Cgamma

Although inositol trisphosphate (IP3) functions in releasing Ca2+ in eggs at fertilization, it is not known how fertilization activates the phospholipase C that produces IP3. To distinguish between a role for PLCgamma, which is activated when its two src homology-2 (SH2) domains bind to an activated tyrosine kinase, and PLCbeta, which is activated by a G protein, we injected starfish eggs with a PLCgamma SH2 domain fusion protein that inhibits activation of PLCgamma. In these eggs, Ca2+ release at fertilization was delayed, or with a high concentration of protein and a low concentration of sperm, completely inhibited. The PLCgammaSH2 protein is a specific inhibitor of PLCgamma in the egg, since it did not inhibit PLCbeta activation of Ca2+ release initiated by the serotonin 2c receptor, or activation of Ca2+ release by IP3 injection. Furthermore, injection of a PLCgamma SH2 domain protein mutated at its phosphotyrosine binding site, or the SH2 domains of another protein (the phosphatase SHP2), did not inhibit Ca2+ release at fertilization. These results indicate that during fertilization of starfish eggs, activation of phospholipase Cgamma by an SH2 domain-mediated process stimulates the production of IP3 that causes intracellular Ca2+ release.

Effects of dietary crude protein, breed, parity, and health status on the fertility of dairy cows

A study was conducted to determine the impact of dietary CP (13% vs. 20%), parity (first vs. second lactation or later), and breed (Holstein vs. Jersey) on the reproductive efficiency of dairy cows. Sixty-four cows were blocked by parity and breed and assigned to one of two treatments. Cows were removed from treatments on d 100 or 120 depending on pregnancy status. Cows were categorized by health status based on the occurrence of postparturient disorders. Plasma urea N concentrations were influenced by diet (8.6 vs. 21 mg/dl, 13 and 20% CP, respectively), parity, and breed. Reproductive indices were not influenced by diet except that days to first estimated ovulation increased for cows fed the 20% CP diet when health status was added to the model. Days to first observed estrus, first AI service, and cumulative pregnancy rate were affected by health status. Regression analysis for survival showed an interaction of diet and health status for days open. High CP diets tended to increase days open when cows had major health problems; otherwise, a high CP diet decreased days open. The implementation of a strict reproductive management program allowed high reproductive efficiency goals to be achieved regardless of plasma urea N concentrations.

Intravascular infusion of lipid into ewes stimulates production of progesterone and prostaglandin

Effects of infusion of a lipid emulsion into ewes during mid-to late diestrus on serum concentrations of total cholesterol (TC), progesterone (P4), prostaglandin (PG) F2 alpha metabolite (PGFM), and PGE2, and on ovulation rate were examined. In experiment 1, ewes received infusions of either saline (S, n = 3) or soybean oil emulsion (SB, n = 3) for 5 h on each of Days 9-13 of the estrous cycle. In experiment 2, ewes received infusions of either S (n = 4), SB (n = 5), or olive oil emulsion (OO, n = 5) for 5 h on each of Days 9 through 15 of the estrous cycle. In both experiment 1 and experiment 2, infusion of lipid increased serum concentrations of TC and P4, which declined with time after infusion was terminated (treatment x hour interaction, experiment 1: TC, p < 0.01, P4, p < 0.01; experiment 2: TC, p < 0.01, P4, p < 0.001). Serum PGFM and PGE2 concentrations were greater in lipid-infused ewes than in controls on Days 13 through 15 (treatment x hour interaction; p < 0.03, p < 0.001, respectively). Duration of the estrous cycle was shortened in OO-infused ewes (16.2 +/- 0.4 days) compared with that of SB- and S-infused ewes (17.2 +/- 0.2 and 18.0 +/- 0.0 days, respectively; p < 0.01). Numbers of corpora lutea and follicles, and diameter of follicles > 4 mm did not differ among treatment groups on Day 14 of the succeeding cycle after infusion. These data indicate that lipid infusion stimulated increases in serum concentrations of TC, P4, and prostaglandins and may shorten the estrous cycle.

Proteases stimulate fertilization-like responses in starfish eggs

Application of proteases to eggs of the starfish, Asterina miniata, caused several responses like those seen at fertilization. Cortical granule exocytosis and fertilization envelope elevation occurred within about 1 min after exposure to trypsin, chymotrypsin, or pronase; protease inhibitors prevented these responses. Kallikrein caused cortical granule exocytosis and fertilization envelope elevation, but this response required more time (congruent to 30 min). Exocytosis was also seen in response to a recombinant trypsin, but not to a point-mutated trypsin without proteolytic activity. The extent of exocytosis was similar to that seen at fertilization, as measured by the fluorescent dye FM 1-43. In addition to causing exocytosis, application of trypsin, chymotrypsin, or pronase caused an increase in intracellular free calcium, detected by calcium green dextran, and stimulation of DNA synthesis, detected by incorporation of bromodeoxyuridine. Exocytosis also occurred when trypsin or chymotrypsin was applied in artificial sea water in which the free calcium was reduced to a low level (40-70 nM) such that Ca influx would be reduce by > 10,000-fold; this indicated that the proteases did not act by damaging the eggs and causing external calcium to leak into the cytoplasm. These findings show that there is an extracellularly exposed protein that when proteolyzed can induce fertilization-like responses; this protein may be a receptor that transduces a signal from the sperm to initiate egg activation at fertilization.

Surface expression of the pre-beta subunit of fertilin is regulated at a post-translational level in guinea pig spermatids

During spermiogenesis in the guinea pig, the spermatid plasma membrane becomes sequentially segregated into three domains of distinct composition. We have previously shown that plasma membrane proteins appear on the cell surface in a temporally regulated manner such that proteins localized to the same domain reach the surface membrane at the same time in sperm development. Fertilin is a cell surface protein restricted to the whole head of testicular sperm; like other proteins restricted to this membrane domain, it does not appear on the cell surface until late (steps 11-13) in spermiogenesis. Using confocal microscopy of immunofluorescently labeled testicular sections, we demonstrate that the pre-beta subunit of fertilin is present in pachytene spermatocytes. It is initially observed in long, strand-like structures that likely represent the endoplasmic reticulum; it later appears in a punctate distribution in the cytoplasm of early spermatids prior to its appearance on the surface membrane in late elongating spermatids. Immunoblotting experiments confirm the presence of the fertilin pre-beta subunit in spermatocytes and early spermatids at the same apparent molecular weight as in later stages. These results suggest that the appearance of fertilin pre-beta subunit on the spermatid surface is regulated by a post-translational mechanism.

Effect of supplemental fish meal on the lactation and reproductive performance of dairy cows

The influence of high protein diets (21% CP, DM basis), containing varied percentages of RUP, on lactation performance and fertility was evaluated. Sixty-two Holstein cows (65% multiparous) were blocked by age and randomly assigned to a 2 x 2 x 2 factorial design from d 12 to 125 postpartum. Factor 1 was 0 or 3.5% fish meal diet, factor 2 was location (Calan door versus free stall), and factor 3 was parity (first versus second or later). The soybean meal diet consisted of alfalfa hay, corn silage, barley, and soybean meal. The fish meal diet contained 3.5% fish meal (ruminant grade menhaden) that replaced a portion of the soybean meal. Cows fed the fish meal diet (40% RUP) had DMI, BW, and body condition similar to those of cows offered the soybean meal diet (34% RUP). Cows receiving the fish meal supplement tended to have higher milk protein production throughout the trial, higher milk production during the first 6 wk, and significantly lower ruminal ammonia concentrations than cows receiving the soybean meal diet. Differences in reproductive performance were not significant except for a diet by housing location interaction for conception rates from first AI.

Changes Occur in the Central Nervous System of the Nudibranch Berghia verrucicornis (Mollusca, Opisthobranchia) During Metamorphosis

The structure of the larval and juvenile central nervous system (CNS) in Berghia verrucicornis, an aeolid nudibranch, was examined using 1-{mu}m serial sections. The CNS consists of paired optic, cerebral, pleural (also known as sub- and supra-intestinal ganglia), pedal, and buccal ganglia, and a single visceral ganglion. A pleurovisceral loop is present. The organization of the CNS changes as the nudibranch undergoes metamorphosis. In general, there is a condensation of the CNS. The cerebral and pleural ganglia fuse to form the prominent cerebropleural ganglia. The single visceral ganglion fuses with the pleural portion of the left cerebropleural ganglion. The buccal ganglia enlarge and fully organize into a cortex of nerve cell bodies and medulla of nerve fibers. Rhinophoral ganglia develop anterior to each cerebropleural ganglion and a pair of nervous processes extend from each: one to the developing rhinophore and the other anteroventral toward the mouth and associated structures. These metamorphic changes are similar to those seen in other commonly studied opisthobranch species, suggesting that Berghia verrucicornis is an appropriate model for the developmental examination of structure and function in molluscan nervous systems.

Evidence for both tyrosine kinase and G-protein-coupled pathways leading to starfish egg activation

To investigate possible pathways leading to egg activation at fertilization, the ability of exogenously introduced tyrosine kinase and G-protein-coupled receptors to mimic events of fertilization was examined. Oocytes of the starfish Asterina miniata were injected with RNA for a chimeric receptor consisting of the extracellular domain of the beta form of the mouse platelet-derived growth factor (PDGF) receptor and the transmembrane/intracellular domain of the human fibroblast growth factor (FGF) receptor, or with RNA for the rat serotonin 1c receptor. These oocytes were cultured for 1 to 3 days and then matured with 1-methyladenine. In response to PDGF or serotonin, the injected eggs underwent responses like those at fertilization: cortical granule exocytosis, a rise in intracellular free calcium, and DNA synthesis. Some of these artificially activated eggs cleaved, and some of the PDGF-activated eggs were observed to form larvae. A PDGF/FGF receptor with a point mutation which eliminated its ability to interact with phospholipase C-gamma did not cause fertilization-like responses. Thus components of a signaling pathway involving phospholipase C-gamma, characteristic of tyrosine kinase receptors, as well as components of a pathway involving a G-protein and phospholipase C-beta, characteristic of G-protein-coupled receptors, appear to be present in starfish eggs. Either or both could function in egg activation at fertilization.

Progesterone production by cultured luteal cells in the presence of bovine low- and high-density lipoproteins purified by heparin affinity chromatography

The objectives of this study were to separate plasma lipoprotein particles based on the presence (low-density lipoproteins; LDL) or absence of apolipoprotein B (high-density lipoproteins; HDL) and to compare the abilities of bovine LDL and HDL to stimulate progesterone production by bovine luteal cells in culture. Plasma lipoproteins were isolated by ultracentrifugation and separated into LDL and HDL by heparin affinity chromatography. Luteal cultures were treated with LDL or HDL cholesterol for 48 h on d 3 of the culture (d 0 = day of dissociation). Progesterone production by luteal cells increased in a dose-dependent manner with increasing concentrations of either LDL or HDL cholesterol. There were no differences in the ability of LDL or HDL cholesterol to stimulate luteal cells to produce progesterone. Because LDL and HDL were equally potent, and experiment was designed to investigate the ability of modified LDL or reconstituted particles without apolipoproteins to stimulate progesterone production. Stimulation of luteal cell progesterone production by lysine-modified LDL was 70% of unmodified LDL. Progesterone production in the presence of phosphatidylcholine liposomes or BSA containing cholesterol was 50 and 108% of that obtained with HDL or LDL. Evidence indicated that apolipoprotein-free particles that contained free cholesterol but not cholesterol esters stimulated luteal cells to produce progesterone.